MATERIALS HANDLING
If the moisture content is higher than 50%, the blade can be raised to cut into slurry or lowered when there is less water present
Proper design enables
users to get the most out of their vibrating screen
WET SCREENING Considerations in wet screening applications are when material is being pumped to a screen or slurry fed to a screen. Tis is a crucial factor in designing the correct static separation device in combination with components to help manage the rate of flow and moisture content.
A feed box with a fixed or curved
sieve that has appropriate screen media placed ahead of a vibrating screen in a wet application will provide uniform distribution. Additionally, it offers benefits from a process standpoint by taking out some of the material before it gets to the
vibrating screen thus increasing the throughput of the combination of static screen and vibrating screen.
Installing a rubber skirt at the feed section of the sieve will aid in slowing the rate of material flow the full length of the screen media
Conn-Weld’s engineering sieves specialist, Robert Riley, explains, “One must understand how the material is being sent to the feed box. Many times, depending on the piping arrangement, it may become necessary to use a manifold to achieve proper distribution. Also, depending on point of entry (front feed, back feed, top feed, etc.), a determination is made as to the positioning of baffles and/or deflectors in the feed box. Once baffles and/or deflectors are located, we then concentrate on slowing the velocity of the material. “Slowing the velocity of material aides in better distribution across the width of the screening surface of the sieve where it is pre-screened before traveling towards the vibrating screen.” Installing a rubber skirt at the feed section of the sieve will aid in slowing the rate of material flow the full length of the screen media, allowing for better screening. Sometimes material will begin to build-up towards the discharge end of the sieve. Tis is fine because while on the discharge end of the screening surface, the material will drain more liquid. Cutter blades ahead of static sieves can assist with removing water before material is presented to a static sieve. Designed with a linear actuator enables the blade to be used dependent upon the moisture content. If the moisture content is higher than 50%, the blade can be raised to
cut into slurry whereas the blade can be lowered when there is less water present. A recent case in point saw an
underground operation having a water issue on its main production shaft belt, which carried 3,400 TPH of coal with an extremely high moisture content. Te water was causing the operator’s load cells to fail. As a result, the belts were overloaded with material. Te solution? Conn-Weld engineered a 5ft6in x 48in x 25° flat fixed sieve with a cutter blade. Te blade extended into the bottom of the flow of material diverting the smaller material onto a CG 5/32in sieve with 5mm OPG. Te end result was that the flat fixed
sieve eliminated up to 90% of the water that once went into the operator’s storage bins.
Conn-Weld provides various types of feed systems with the knowledge of how to get the most out of vibrating screen equipment, therefore bringing value to the overall operation. Introducing an interface between the source of feed and the vibrating screen will result in extended wear life and maximum efficiency.
Marvin Woodie is president of Conn-Weld.
www.conn-weld.com
www.engineerlive.com 43
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